I'm not sure why the applications are not showing in admin mode but I suggest you just modify the configuration file directly, as explained in the EHS settings documentation.
- Pull the current file from the device via adb pull
- Add your applications to the <applications> tag in the config XML file
- Push the modified file back to the device, overwriting the existing configuration via adb push
You should not need any special resources or signing requirements unless you are running in secure mode, which is off by default.
As it turns out, the problem with visibility was that I had used an XML vector drawable for the launcher icon in in those apps. Once I generated all the DPIs of a .png format icon from that vector image, and changed the Manifest (I used a new name for the bitmaps as I wanted to be sure it didn't reference the vector version at all, but this may not have been needed), then they showed up.